Allocation Group¶
Allocation Group is the way to apply additional uniqueness limitation for various logical resources allocation:
- VLAN
- IP Address
- IP Prefixes
Allocation Groups are used to avoid possible conflicts and intersections when connecting various parts of the network
Mobile Network Address Plan¶
Mobile networks often use 3 VRFs to separate various types of traffic and imply additional network processing, namely:
- Network Management
- Voice
- Mobile data
Prefixes and address allocation in each VRF performed independentently by default. So its easy to allocate same prefixes and addresses in different VRFs. While the address plan independentence is a core concept of VRF, it can lead to various practical problems:
- Network equipment may not be aware of VRFs at all and cannot reuse same addresses or networks for different purposes (like Voice and Management for SBCs)
- Possible traffic leaking due to configuration mistakes
- Complicated traffic analysis
Solution is to create common Allocation Group and apply it to all 3 VRFs. So same network can be allocated only in one VRF, ensuring network uniqueness
Common VLAN space¶
Consider several Points-of-Presence (Branch offices, datacenters, etc) connected by equipment incapable of VLAN tag manipulation. Any VLAN from one PoP may be extended to another PoP any time. If same VLAN may be allocated for different purpose at different PoPs there will be problem when trying to extend any of VLANs, requiring expensive VLAN renumbering at one PoP.
Solution is to create common Allocation Group and apply it to appropriate PoP's segments. So same VLAN can be allocated only in one PoP, ensuring VLAN uniqueness